Fixing the busybox build failure

Since a few months I have a build failure every time I try to generate an initial ram file system (as my current primary workstation uses a separate /usr and LVM for everything except /boot):

* busybox: >> Compiling...
* ERROR: Failed to compile the "all" target...
* 
* -- Grepping log... --
* 
*           - busybox-1.7.4-signal-hack.patch …
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